In wireless communication networks, e.g., based on radio technologies as specified by 3GPP (3rd Generation Partnership Project), various kinds of control information are used for controlling radio transmission. In the LTE (Long Term Evolution) radio technology, Downlink control information (DCI) is transmitted on a PDCCH (Physical Downlink Control Channel) or EPDCCH (Enhanced Physical Downlink Control Channel) established between the wireless communication network and a UE (user equipment), as for example specified in 3GPP TS 36.211 V13.0.0 (2015-12). The DCI may for example be used to provide an uplink scheduling grant (UL SG) and/or a downlink scheduling assignment (DL SA) to the UE. The UL SG indicates radio resources which are assigned to the UE for a radio transmission in an uplink (UL) direction from the UE to the wireless communication network. The DL SA indicates radio resources which are assigned to the UE for a radio transmission in a downlink (DL) direction from the wireless communication network to the UE. In the time domain, the radio transmissions are organized in radio frames composed of multiple subframes, and the PDCCH is transmitted in a control region typically located in the first (one, two or three) OFDM (Orthogonal Frequency Division Multiplexing) symbols of each subframe. As defined in 3GPP TS 26.213 (2015-12), the DCI for a certain UE can be transmitted in a UE specific search space, using one of several possible DCI formats. Since UE does not know which resource elements in the search space were used for transmitting the DCI and which DCI format was used, the UE performs blind decoding over the search space until correctly receiving the DCI. In the case of the PDCCH, the UE specific search space is derived by the UE from its identity and a subframe number. For the EPDCCH, UE specific search spaces may be signalled in an RRC (Radio Resource Control) message to the UE, using the “EPDCCH-Config” information element as for example defined in 3GPP TS 36.331 V13.0.0 (2015-12). The UE specific search spaces extend over the same time domain range, in the case of the PDCCH over the entire control region of the subframe, and in the case of the EPDCCH over the data region of the subframe, i.e., the part of the subframe which is not assigned as control region.
With further evolution of wireless communication systems, there is an increasing demand of efficiently supporting various kinds of application scenarios. One example of such application scenarios is reliable ultra-low delay machine-type communication (MTC), also referred to as Critical-MTC or C-MTC. For C-MTC, it is desirable to specifically support sporadic latency transmissions of data with low latency and to manage coexistence of such latency critical transmissions with non-critical transmissions of data, e.g., best-effort traffic. While this issue may be addressed by prioritizing the latency critical transmissions over the non-critical transmissions, there is still a risk that the blind decoding process for receiving the required DCI, e.g., a DL SA or UL SG, causes excessive delay.
Accordingly, there is a need for techniques which allow for efficiently controlling radio transmissions in scenarios where UEs are subject to specific timing requirements, such as low latency.